What is a transom in a door?

Author: Koby Green  |  Last update: Wednesday, December 17, 2025

Generally speaking, a transom is a horizontal crossbar that is generally used above a door to separate it from a window. Many different types of transoms serve various amount of functions.

What is the function of a transom?

Builders historically installed transom windows in homes to allow air to flow through the house with the doors closed. They appeared predominantly in row houses that didn't have many windows. Today, transom windows are used to add natural light to your home.

Why did doors used to have transoms?

Old houses often feature windows above doors, known as transom windows, for several reasons: Natural Light: Transom windows allow additional natural light into the entryway or hallway, making the space feel brighter and more inviting. Ventilation: They can provide ventilation, especially in warmer climates.

Can I replace a door without replacing the transom?

In many cases, replacing the door doesn't mean you have to replace everything. On the other hand, if the sidelights and transom are in poor condition or you're not happy with the way they look, replacing all three may be the best way to go.

What is the use of a transom?

Transoms separate doors from windows above the door and allow extra light to enter your home when they are placed above exterior windows. The windows are generally rectangular and placed horizontally, and may be sectioned with trim. Door transoms can be used on interior doors, and these are mainly ornamental in nature.

Transom door magnetic hold-open latch

What is a transom for a door?

In architecture, a transom is a transverse horizontal structural beam or bar, or a crosspiece separating a door from a window above it. This contrasts with a mullion, a vertical structural member.

Why is it called a transom?

Early carpenters referred to the beam above a front door as the "transom". When carpenters began adding windows above this beam they called them "transom windows." Today "transom window" refers to most any auxiliary window (interior or exterior) whether it be placed over a door, above an opening, alone in a wall, etc.

How much does it cost to replace transom?

On a larger boat, you could be looking anywhere from $5000-$15,000.

What does a bad transom look like?

Observe if the transom compresses around the engine bolts; Observe for cracking on the fibreglass around the engine bolts; Washers are often observed as being compressed into the transom in areas where the timber has lost its strength. Remove some screws or an engine bolt to observe if water spits out of the hull.

Can you fix a rotten transom?

Repairing A Rotted Transom

One method is to use a product like Git-Rot from BoatLIFE. This two-part liquid epoxy fills and restores the dry rot inside the wood using capillary action to penetrate it without drilling it full of holes.

What is the point of a transom?

A transom can serve two purposes. To better the structural integrity of a building or to serve as an ornamental piece that betters the overall visual appeal of a building's architecture.

What is the little window in a door called?

a peephole or a very small window in a door. Also called: judas window, judas hole.

Are transoms outdated?

No, transom windows are not outdated. While they're a traditional architectural feature, many modern homes incorporate transom windows in their designs. Not only do they add aesthetic appeal, but they also increase the amount of natural light and can enhance ventilation.

What is the window above a door called?

Transom windows (also called transom lights) sit above an entry, patio or interior door, or other windows. Typically non-operating and used to add style and increase natural light, transoms span the width of the opening they top and can be placed above single or double doors and sidelites.

Do I need a transom?

If you can trim your engine all the way down when towing, you very well might not need a transom saver or motor support. However, if the lower unit of your outboard engine is too close to the ground when trimmed down, your engine is at high risk of damage during trailering.

What is the stone above a window called?

Cast Stone Heads and Lintels. A window head is the stone which spans the aperture above a window, and a door head spans the aperture above the door. These are non-structural decorative features that enhance the visual appearance of a project.

What are the two holes for the transom?

The one on the right is for draining the water out of your boat (bilge drain), the other one will be for a bait tank or raw water wash down (hope its capped of well).

What is a structural transom?

Transoms are typically horizontal tubes which span across the ledgers. They are normally at right angles and they are usually positioned to face a building. Much like ledgers and standards, they are essential when it comes to the safety and strength of the scaffolding structure.

How to check transom?

If there is no motor, then poke the holes in the transom with a screw driver to see if the wood there is soft. Also, a knock on the transom with your hand or a rubber mallet. You can here a hollow sound if it there is a problem. Finally, the sure way to know the condition is to have it surveyed.

What does a rotten transom look like?

Bad rot will lead to totally deteriorated wood and a lot of flex in the transom when the outdrive unit is under load. If you're not experiencing that, then your transom overall is probably okay. You can probe with a piece of stiff wire around the screw holes and see if there is any severe softness.

Can a transom be replaced?

This is handy to know as the same resin is ideal to use to carry out your tranome repair/replacement. The adhesion will be fine, the working time will be achievable to work with and you will be keeping it same/same. The most common resin we get asked to replace a transom with is epoxy.

How do you secure a transom?

just open the quick release buckle, pull the adjustable transom tie down strap snug, and flip the buckle closed. Then It will tighten and lock automatically, keep the stern of your boat secured to your trailer, prevents boat bouncing and shifting on the trailer.

Why do old houses have windows above doors?

Historically, operable transom windows above doors played a role in the heating and cooling in a home. Operable transoms have sashes that can be opened or closed to help regulate the temperature in a room when the door is closed.

Why did doors have transoms?

Transom Doors are doors with windows that open above them. The purpose of a transom window is usually decorative, located in the upper section of a door. Transom windows can be used in place of a full window or as an accent in a room where lower visibility isn't ideal.

What is the difference between a clerestory and a transom?

Clerestory windows are windows placed high on a wall, above eye level. In the spirit of clearing the air, these windows are not to be confused with transom windows which are those placed above a window or door.

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